The polyphenols in fruits and vegetables may be partly responsible for the health-promoting effects attributed to fruit and vegetable intake. Although their properties have been relatively well studied, the activity of their metabolites, produced after ingestion, has been poorly investigated. Thus, the aim of this work was to study the potential anti-inflammatory effect of 18 polyphenol metabolites, derived from colon microbiota. They were screened by measuring prostaglandin E(2) (PGE(2)) production by CCD-18 colon fibroblast cells stimulated with IL-1beta. Metabolites that inhibited more than 50% PGE(2) production were hydrocaffeic (HCAF), dihydroxyphenyl acetic (dOHPA), and hydroferulic acid (HFER), that subsequently were tested with the writhing and paw pressure test in rodents where all three compounds showed an anti-inflammatory effect. The effect of HCAF administered orally (50 mg/kg) was also tested in the dextran sodium sulfate (DSS)-induced colitis model. Weight loss and fecal water content were more pronounced in DSS rats than in DSS-HCAF treated rats. HCAF treatment diminished the expression of the cytokines IL-1beta, IL-8, and TNF-alpha, reduced malonyldialdehyde (MDA) levels and oxidative DNA damage (measured as 8-oxo-2'-deoxyguanosine levels) in distal colon mucosa. These results indicate that HCAF, dOHPA, and HFER have anti-inflammatory activity in vitro and in vivo.

Low molecular weight phosphotyrosine-protein phosphatase (LMW-PTP) shares no general sequence homology with other PTPs, although it has an active site sequence motif CXXXXXR and a reaction mechanism identical to those of all PTPs. The main function of this enzyme is the down-regulation of platelet-derived growth factor and insulin receptors. Both human LMW-PTP isoenzymes are inactivated by H 2 O 2 . The enzymes are protected from inactivation by P i , a competitive inhibitor, suggesting that the H 2 O 2 reaction is directed to active site. Analysis of free thiols performed on the inactivated enzymes demonstrates that only two out of the eight LMW-PTP cysteines are modified. Time-course high performance liquid chromatography-electrospray mass spectrometry, together with specific radiolabeling and tryptic fingerprint analyses, enables us to demonstrate that H 2 O 2 causes the oxidation of Cys-12 and Cys-17 to form a disulfide bond. Because both residues are localized into the active site region, this modification inactivates the enzyme. Fluorescence spectroscopy experiments suggest that the fold of the enzyme is modified during oxidation by H 2 O 2 . Because a physiological concentration of H 2 O 2 produces enzyme inactivation and considering that the activity is restored by reduction with low molecular weight thiols, we suggest that oxidative stress conditions and other processes producing hydrogen peroxide regulate the LMW-PTP in the cell.Protein tyrosine phosphorylation in eucaryotes is a key mechanism for cellular control, because it is involved in several processes, such as cellular metabolism, proliferation, differentiation, and oncogenic transformation (1). A fine balancing of cellular protein tyrosine phosphorylation levels is determined by regulating the activities of protein-tyrosine kinases and/or protein-tyrosine phosphatases (PTPs).1 Receptor protein-tyrosine kinases are considered to be the major enzymes regulating mitogenic protein phosphorylation cascades; nevertheless, the presence of SH2 domains in particular PTPs and the receptorlike structure of some membrane PTPs clearly indicate that PTPs are also regulated in the cell. The PTP superfamily consists of four main families: the tyrosine-specific phosphatases, the VH1-like dual specificity phosphatases, the cdc25 phosphatases, and the low molecular weight phosphatases (LMW-PTPs). Despite extremely limited sequence similarity, all share an active site motif consisting of a cysteine and an arginine separated by five residues (CXXXXXR, where X is any amino acid). All PTPs have identical catalytic mechanism, which involves the formation of a cysteinyl-phosphate intermediate (2).Recent papers from our laboratory have demonstrated that LMW-PTP is involved in the regulation of cellular signaling started by the activation of PDGF and insulin receptors (3-5). In fact, the overexpression of the wild type enzyme in NIH/3T3 cells causes decrease of cellular growth rate and of phosphorylation level of the PDGF receptor (3). Furthermore, the overexpression in ...

The interactions of cisplatin and its analogues, transplatin, carboplatin and oxaliplatin, with hen egg white lysozyme were analysed through ESI mass spectrometry, and the resulting metallodrug-protein adducts identified; the X-ray crystal structure of the cisplatin lysozyme derivative, solved at 1.9 A resolution, reveals selective platination of imidazole Nepsilon of His15.

No abstract

The primary structure of some new lipodepsipeptides named syringopeptins, produced by plant pathogenic strains of Pseudomonas syringae pv. syringae has been determined by a combination of chemical methods, 'H and 13C NMR spectroscopy and FAB mass spectrometry. Two syringomycin-producingwith Tyr acylating aThr to form a macrolactone ring, and smaller amounts of the 3-hydroxydodccanoyl homologue. Evidence was obtained that a third syringomycin-producing strain and a syringotoxin-producing strain synthesize 3-hydroxydecanoyl-Dhb-Pro-Val-Ala-AlaVal-Leu-Ala-Ala-Dhb-Val-Dhb-Ala-Val-Ala-Ala-Dhb-aThr-Ser-Ala-Vnl~~Ala-Dab-Dab-Tyr, with Tyr and aThr forming again the macrolactone ring, and smaller amounts of the 3-hydroxydodecanoyl homologue.Phytotoxin; Lipodepsipeptide; Syringopeptin; Pseudomonas syringae pv. syringae